Thermometer



G. E FORD May 16, 1939.

THERMOMETER Filed Feb. 28, 1938 NVENT OR CS ;M

A TTORNEY Patented May 16, 1939 THEBMOMETER George E. Ford, Rochester,N. Y., assinor to Rochester Manufacturing Co., Inc., Rochester, N. Y., acorporation of New York Application February 28. 1938, Serial No. 1923932 Claims.

This invention relates to a thermometer. and has to do more particularlywith thermometers of metallic construction of the type employing ahelical coil of either bimetallic or other construction that isconnected to an indicator to eifect movement thereof.

One object of the invention is to afford a construction that is ofsimple and practical design, reliable and accurate, and protectedagainst breakage or damage during shipment.

More particularly, the invention has for its purpose to surround boththe inside and outside surfaces of the helical coil with a housing thatis close th'ereto, so as to reduce the amount of lag and give a correctreading and greater accuracy in a shorter period of time than withinstruments heretofore employed for the purpose.

Another purpose of the invention is to. aford a more sensitiveinstrument by substantially reducing the dead ai space within thehelical coil,

thus making the heat responsive element more sensitive to any fluidwhose temperature is to be determined, and equalizing the eifect on theoutside and inside surfaces of the coil.

Another object of the invention is to aiord a. construction in which theheat sensitive element is efllciently insulated from the indicator andindicator-housing, and the parts are so constructed that the helicalcoil as well as the indicator-shaft are protected against breakage ordeformation during shipment, or from excessively rough handling.

To these and other ends, the invention consists in the Construction andarrangement of parts that will appear from the following descriptionwhen read in conjunction with the accompanying drawing, the novelfeatures being pointed out in the claims following the speciflcation.

In the drawing:

Fig. 1 is a sectional view of a thermometer showing one practicalembodiment of the invention;

Fig. 2 is a detail sectional view showing the connection between theindicator-shaft and helical coil, and

Fig. 3 is a detail view showing the position of the parts when theindicator-shaft has moved endwise into contact with the inner wall ofthe helical coil housing.

Referring more particularly to the drawing, in which like referencenumerals refer to the same parts throughout the several views, ldesignates the indicator-shaft provided with the usual indicator 2located within the indicator-housing 3. The indicator-shaft I isslidably and rotatably mounted in a bushing 4 that is threaded at 5 topermit it to be inserted into a receptacle.

The inner end of the indicator-shaft is connected to the inner end ofthe helical coil 8, which may be bimetallic, or of hollowfluid-containing metal, or otherwise formed, the outer end of the latterbeing fixedly connected at 'I to the helical coil housing.

said housing includes a head or end portion 8 to which are suitably andpermanently attached an outer cylindrical wall 9 and an inner'cylindrical wall Il), both of suitable thin metal. The inner wall n hasa closed inner end II afiordng a chamber into which liquids or fiuidsmay enter and circulate through the opening !2. The inner wall !0 islocated within and in close p'oximity to the inner surface of thehelical coil 6 while the outer wall 9 surrounds the helical coil and isin close proximity thereto, the inner and outer walls affording a meansthat effectively prevents distortion or deformation of the coil ineither direction transversely of its length, due to jars in shipment orexcessively rough usage.

Owing to the cylindrical inner wall io and the chamber which itencloses, permitting access of liquids or fluids, the latter are broughtinto close proximity to the inner surface of the bimetallic coil,causing both the inner and outer portions of the coil to respond quicklyand uniformly to the temperature of the fluid that is undergoing testwhich makes for quicker action and greater accuracy.

With this arrangement, the indicator-shaft l is made of minimum length,extending but little beyond the portion of the helical coil to which itis connected, and the endwise movement of the indicator-shaft that maytake place due to contraction of the helical coil is limited by theclosed end ll of the inner wall of the chamber, thus aflording a furtherprotection against deformation or Injury of the delicate parts of theinstrument.

In order to afiord a still more accurate reading and to insulate theheat sensitive member from the indicator-shaft and indicator-housing, Iemploy insulating means surrounding the end of the helical coil where itis connected to the indicator-shaft. Such insulating means is shown atl3, and may consist of heat resisting fiber or suitable lacquer, paintor other insulating medium interposed between the surfaces of the coiland the surfaces of the indicator-shaft to which it is jo'ned. This actsto measurably prevent the conducting of heat from the indicator-housingand outside atmosphere through the indicatorshaft to the helical coil.and tends to insure a more accurate reading ot the temperature oi theliquid or fluid into which the helical coil and its surrounding housingis inserted.

while the invention has been described with reference to a structuralembodiment, it is not limited to the details shown, and this applicationis intended to cover such modiilcations as may come within the purposeso! the improvement or the sccpe o! the following claims.

I claim:

1. In a thermometer, the combination with a threaded bushing adapted tobe secured in a receptacle. o! an indicator shait supported by saidbushing and rotatable therein, a housing comprising an outer cylindricalwall mounted on said bushing, a head located within and secured to theouter end of said outer cylindrical wall, an inner cylindrical wallsecured to the inner end oi said head and closed at its inner end. and atemperature responsive heiical coil having its inner end secured to saidindicator shaft and its outer end secured to said head at a pointbetween the inner and outer cylindricai walla, the

inner closed end of theinner wall acting as a. stop to limit endwisemovement 01' the indicatcr shaft which is free to move thereagainst. e)

2. In a thermometer. the combintion with a. threaded bushing adapted tobe secured in a receptacle, of an indicator shaft supported by andrctatable in said bushing. a housing comprising sn outer cylindricalwall secured to said bushing, a head located within and secured to theouter end of said cuter wall. said head having a. reduced cylindricalinner end portion and an intermediate cylindrical portion between itsends, an inner cylindrical wall secured to the inner end of said head,and a temperature responsive helical coil having its outer end securedto said intermediate cylindrical portion of the head between the innerand outer walls and its inner end secured to said indicator shhit, theinner end of the inner cylindrical wall being closed and acting as astop to limit endwise movement ot the indicator shaft and said shattbeing free to move into engagement with said stop.

GEORGE E. FORD.

